Which expression is equilvalent 64^3/2

Yuri, sam and dani had the same math homework last night, but none of them finished it. yuri finished 3/8 of her homework, sam finished 4/6 of her homework and dani finished 1/2. who finished the most math homework? who finished the least amount?

Arestaurant gives out a scratch-off card to every customer. the probability that a customer will win a prize from a scratch-off card is 25%. design and conduct a simulation using random numbers to find the experimental probability that a customer will need more than 3 cards in order to win a prize. justify the model for your simulation, and conduct at least 10 trials.

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?